Ethyl bromide, hydrolysis

Hydrolysis of Ethyl Bromide. Add -a few drops of pure freshly distilled ethyl bromide to 2-3 ml. of aqueous silver nitrate solution in a test-tube and shake. Only a faint opalescence of silver bromide should be formed. -Now carefully warm the mixture in a small Bunsen flame, with gentle shaking silver bromide soon appears as a white suspension which rapidly increases in quantity and becomes a heavy precipitate. The ethyl bromide is thus moderately stable in cold water, but rapidly hydrolysed by hot water. 

Primary carbocations are so high m energy that their intermediacy m nucleophilic substitution reactions is unlikely When ethyl bromide undergoes hydrolysis m aqueous formic acid substitution probably takes place by an 8 2 like process m which water is the nucleophile... 

This ether was prepared from an alcohol and 2-(phenylselenyl)ethyl bromide (AgN03, CH3CN, 20°, 10-15 min, 80-90% yield) it is cleaved by oxidation (H2O2, 1 h ozone or NaI04), followed by acidic hydrolysis of the intermediate vinyl ether (dil. HCl, 65-70% yield). ... 

An early application of this reaction to the preparation of barbiturates starts by the condensation of the ketone, I21, with ethyl cyanoacetate by Knoevenagel condensation. Alkylation of the product (122) with ethyl bromide by means of sodium ethoxide affords 123. Condensation of this intermediate with guanidine in the presence of sodium ethoxide gives the diimino analog of a barbiturate (124). Hydrolysis affords vinbarbital (111). > ... 

P.M. Jeffers and N.L. Wolfe, Hydrolysis of methyl bromide, ethyl bromide, chloropicrin, 1,4-dichloro-2-butene, and other halogenated hydrocarbons, in Fumigants Environmental Fate, Exposure, and Analysis, ed. J.N. Seiber, J.A. Knuteson, J.E. Woodrow, N.L. Wolfe, M.V. Yates, and S.R. Yates, ACS Symposium Series No. 652, American Chemical Society, Washington, DC, pp. 32-41 (1997). 

To ascertain whether tritium could have entered the polyisobutylenes by a process other than the hydrolysis of a carbon-aluminium bond, we tested the reaction of suitable polymers with aluminium bromide. The polyisobutylenes were dissolved in ethyl bromide, and phials of aluminium bromide were crushed into these solutions, which were subsequently kept at 0 °C for ca. 15 minutes, and then hydrolysed in the usual way with tritiated water. The three substances examined in this way were polyisobutylenes of high and low DP, and nonadecane. The polyisobutylenes contain approximately one double bond per molecule. The results in... 

Catalytic effects.—Within certain limits, the stimulating action exerted by the presence of hydrochloric acid upon the speed of inversion of cane sugar 28 is less the more dil. the acid. Thus, W. Ostwald found the velocity constant with a soln. containing a mol. of acid per 2 litres of soln. is 20 52 per 10 litres, 3 335 and per 100 litres, 0 3128. The action is favoured by the presence of neutral salts, and this the more, the lower the mol. wt. of the salt in the same family group of the periodic system. The temp, coeff. of the inversion is 17 92 at 100°, and. 0 04104 at 25°. W. Ostwald, R. Hopke, and H. Trey have likewise studied the accelerating influence of the acid on the hydrolysis of methyl and ethyl acetates. Similar studies have been made by W. Ostwald and A. Villiers on the hydrolysis of methyl and ethyl acetates, calcium oxalate, and ethyl bromide and iodide. 

Rates of Hydrolysis of Alkyl Bromides in Water at 50° Relative to Ethyl Bromide... 

Cordes, etal also employed poly-4-vinylpyridine alkylated with lauryl bromide and ethyl bromide (PVP-Ljj, 27) for the hydrolysis of p-nitrophenyl hexanoate (23,... 

If liquid ethyl bromide is shaken with water at 25 C, no appreciable reaction takes place even after several days. The aciiieous phase will not show a Br test with Ag+, and the original reactants may be recovered unchanged. With -butyl bromide, on the other hand, one finds a fairly vigorous reaction with water at 25°C, accompanied by the liberation of heat, to produce -butyl alcohol and HBr. With bcnzhydryl bromide, (CeH6)2CHBr, the hydrolysis reaction appears to be almost immeasurably fast. Although all of these reactions can be represented stoichiometrically by the same general equation,... 

The alkylation of nitriles has been developed as a general method for the preparation of substituted acetonitriles. An excellent discussion of the literature to 1937 has been given. The procedure consists in treating a nitrile in an inert solvent with finely divided sodium amide and the halogenated compound, followed by careful hydrolysis with water. Common solvents are ether, benzene, toluene, or liquid ammonia. Mono-, di-, and tri-alkylated products are possible, as shown by the alkylation of acetonitrile with ethyl bromide however, the mixtures can often be separated by fractional distillation. 

Problem 14.7 In 80% ethanol at SS", the second-order rate constant for the reaction of ethyl bromide with hydroxide ion is 0.0017 liters/mole/sec. Making use of this rate constant and those in Sec. 14.8 and Problem 14.4, calculate the relative rates of hydrolysis in 0.1 N hydroxide for methyl, ethyl, isopropyl, and rerr-butyl bromides. 

Bimolecular transition state for hydrolysis of ethyl bromide... 

Phenobarbital is prepared by treating benzyl ehloride with sodium eyanide when benzyl eyanide (or a-phenyl acetonitrile) is formed with the elimination of a moleeule of sodium chloride. Benzyl cyanide, first on hydrolysis yields phenyl aeetic acid which on subsequent esterification with ethanol forms the eorresponding ester as ethyl phenyl acetate. This on reaction with diethyl oxalate in the persence of absolute ethanol and sodium metal gives diethyl phenyl oxalo acetate which on distillation at 180°C results into phenyl malonic ester. When it is treated with ethyl bromide and sodium ethoxide, the lonely active hydrogen atom gets replaced with an ethyl group thus forming ethyl phenyl malonic ester. Lastly, this on condensation with urea loses two molecules of ethanol and finally forms the desired compound phenobarbital. 

Adapt the preceding mechanism for the hydrolysis of RX so that it describes the methanolysis of ethyl bromide. 

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